<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>CSS值与单位</title>
    <link rel="stylesheet" href="./styles/css04_value.css">
</head>
<body>
    <h1>CSS值与单位</h1>
    <ul class="ems">
        <li>选项1</li>
        <li>选项2</li>
        <li>选项3
            <ul class="rems">
                <li>子选项1</li>
                <li>子选项2</li>
            </ul>
        </li>
    </ul>

    <p class="color_demo">颜色值</p>
    <div class="box bg_image">图像背景</div>
    <div class="box bg_gradient">图形背景</div>
</body>
</html>